Drying Rates of Ephemeral Wetlands: Implications for Breeding Amphibians

Abstract

Ephemeral wetlands provide breeding habitat for many amphibian species, and wetland hydrology plays a crucial role in determining amphibian breeding success. We discuss the potential influence of recession rates (i.e., rate of water level decline) and empirically evaluate them in wetlands inhabited by the endangered reticulated flatwoods salamander (Ambystoma bishopi). Rapid water level declines are potentially problematic for reticulated flatwoods salamanders because this species has a long development period, with metamorphosis generally occurring from March to May when groundwater losses are combined with high evapotranspiration rates. To evaluate magnitude, variability, and drivers of recession rates, we monitored water levels in 33 wetlands in the Florida panhandle and examined recession rates during the flatwoods salamander reproductive period. After controlling for the effects of specific yield, standardized recession rates were, on average, 3.9 times daily potential evapotranspiration rates, suggesting that groundwater fluxes are an important driver of water level declines in these wetlands. Standardized recession rates were variable across the landscape and increased with decreasing wetland size, indicating that larger wetlands are often hydrologically more suitable for flatwoods salamanders. This work points to these and other controls on wetland recession rates and their role in regulating amphibian reproductive success.